Field of the Invention
The invention relates to an improvement in the quality of friction stirring tools in friction stir welding.
Description of the Prior Art
At the beginning of the nineties of the last century, friction stir welding was developed. In the meantime, friction stir welding is being successfully used among other things for the welding of aluminum alloys in many relevant areas of industry. The applications range here from one-off pieces and small batches through to larger batches. Apart from the outstanding quality of the weld seam, other factors contributing to the commercial success are the high degree of reproducibility and the little preparational work and expenditure on finishing. This method can be automated very well and allows quality monitoring on the basis of machine monitoring.
In friction stir welding, frictional heat is generated in the joining region of the materials to be connected by means of the friction between a rotating tool which at the same time is moved translationally and applied with pressure. The tool is moved along the joining region and stirs the plastified material in the interior of the seam of the materials to be connected that are butting against one another. The applied pressure presses the plastified material together. At the end of this seam, the tool is withdrawn from the region of the connection and the weld seam can be subjected to loading immediately.
DE 10 2004 030 381 B3 discloses a method for online quality testing in friction stir welding that is based on the object of being reliable and simple.
To achieve this object, it is claimed that a friction stirring tool is introduced under rotational movement and applied pressure into the material of workpieces to be welded and is guided along a joint of the workpieces to be welded, the application of pressure and/or the oscillations of the friction stirring tool that occur during the friction stir welding process, of the workpieces to be welded or of other elements that are excited by the welding process being measured over time and subsequently converted by means of a Fourier transform into frequency-amplitude spectra, and that the frequency-amplitude spectra determined are compared with reference values for testing the quality of the welded connection produced.
Furthermore, DE 603 10 020 T2 discloses a method for connecting structural components by means of friction welding with a connecting plug, in which a method for producing a structural assembly that comprises the following features is claimed.
Positioning a first structural element at least partially adjacent a second structural element to define an interface therebetween and inserting a rotating plug into the first and second structural elements at the interface to thereby form a friction plug welded connection that connects the first structural element to the second structural element, and after that the following feature is lastly claimed.
The forming of an elongate welded connection between the first and second structural elements along the interface, wherein the elongate weld joint at least partially consumes the plug.
Furthermore, WO 2007/006669 A1 discloses a friction stir welding tool and also a method and an assembly for the real-time control of a friction stir welding process by recording the forces of acceleration and/or oscillations at the tool body.
This invention is based on the object of providing a compact friction stir welding tool for universal application and also a method and an assembly for the real-time control of a friction stir welding process that succeed in optimizing the joining process in a simple and low-cost manner, so that it produces a joining weld that conforms to quality requirements without the need for subsequent finishing and minimizes the stress exerted on the friction stir welding installation.
This object is achieved with a friction stir welding tool consisting of a tool main body and a tool stirring stud with a shoulder and a pin, which according to claim 1 is characterized in that at least one sensor for recording the forces of acceleration acting on the tool main body is integrated in the tool main body.
The service life of the tool stirring tool is not taken into account in the known prior art.